Sauli Vuoti

Chemical modification of cellulosic fibers for better convertibility in packaging applications

Cellulose fiber has been modified by mechanical and chemical means in order to improve paper properties, which respond to moisture and temperature. When the cellulose is first refined and then etherified using hydroxypropylation under dry conditions, the paper sheets prepared from the hydroxypropylated cellulose show improved elongation. When the level of hydroxypropylation is high enough, the paper sheets also become transparent. Additionally, the effect of cellulose activation using different mechanical methods has been compared by esterification reactions. It is shown that removal of water is the most crucial step for the esterification reactions while other methods have a lesser impact. The paper sheets prepared from the esterified cellulose fibers show an increase in contact angles and high hydrophobicity.

Two isomers of Pd2(S2NC7H4)4.

The dichloromethane solvates of the isomers tetrakis(mu-1,3-benzothiazole-2-thiolato)-kappa(4)N:S;kappa(4)S:N-dipalladium(II)(Pd-Pd), (I), and tetrakis(mu-1,3-benzothiazole-2-thiolato)-kappa(6)N:S;kappa(2)S:N-dipalladium(II)(Pd-Pd), (II), both [Pd2(C7H4NS2)4] x CH2Cl2, have been synthesized in the presence of (o-isopropylphenyl)diphenylphosphane and (o-methylphenyl)diphenylphosphane. Both isomers form a lantern-type structure, where isomer (I) displays a regular and symmetric coordination and isomer (II) an asymmetric and distorted structure. In (I), sitting on an centre of inversion, two 1,3-benzothiazole-2-thiolate units are bonded by a Pd-N bond to one Pd atom and by a Pd-S bond to the other Pd atom, and the other two benzothiazolethiolate units are bonded to the same Pd atoms by, respectively, a Pd-S and a Pd-N bond. In (II), three benzothiazolethiolate units are bonded by a Pd-N bond to one Pd atom and by a Pd-S bond to the other Pd atom, and the fourth benzothiazolethiolate unit is bonded to the same Pd atoms by, respectively, a Pd-S bond and a Pd-N bond.

Synthesis and melt processing of cellulose esters for preparation of thermoforming materials and extended drug release tablets

Using softwood pulp as the starting material, the synthesis of regioselectively substituted mixed cellulose esters with varying degree of substitution and ratio of short/long chains was successfully completed. The structures of the cellulose esters were characterised. The impact of the structural changes and the degree of substitution of the cellulose esters on thermal properties and processability were investigated. The study shows that the sequential esterification is a promising modification route for cellulose to improve its thermal processability and mechanical properties without the use of external processing aids such as plasticisers. In particular, the hexanoate group in the C6 position on the cellulose backbone acts as an internal plasticiser and improves thermal processability and increases the strength and stiffness of the cellulose ester. The properties of sequentially esterified cellulose promote its practical use in plastics, coatings, films and drug delivery. Sequentially esterified cellulose hexanoate-acetate was used successfully in a coating formulation for the preparation of tablets and showed a stable extended release profile for three water-insoluble drugs in this context. The pH of the release medium had no notable effect on the release properties.

(E)-1-(4-Amino­phen­yl)ethanone oxime

In the molecule of the title compound, C8H10N2O, the oxime group is oriented at a dihedral angle of 5.58 (3)° with respect to the benzene ring. In the crystal structure, intermolecular O—H⋯N and N—H⋯O hydrogen bonds link the molecules, forming a three-dimensional network.

4-(4-Chlorophenyl)-3-(3-methoxybenzyl)-1H-1,2,4-triazole-5(4H)-thione

The title compound, C16H14ClN3OS, is an important, biologically active heterocyclic compound. The triazole ring is oriented at dihedral angles of 66.65 (3) and 82.53 (3) with respect to the 4-chlorophenyl and 2-(3-methoxyphenyl)methyl rings, respectively. The dihedral angle between the benzene rings is 32.90 (2) . In the crystal structure, intermolecular N— H S hydrogen bonds link the molecules into centrosymmetric dimers.